Chapter 4 Biology Lab I Midterm

Resolving power

Microscopes allow us to see things that our eyes would not be able to see unaided. Our eyes are limited by this.

Field of vision

Allows you to estimate an object's size in view. As magnification increases, this term decreases. If you know its diameter, you can estimate the size of an object in view. As magnification changes, so does the diameter of this.

Depth of field

Thickness of a specimen that can be viewed within one plane of focus. As magnification increases, this term decreases. Changes as magnification changes.

Arm/base

supports the body tube

Main switch

turns the light on

Light intensity knob

How high or low do you want the light to be

Y-axis stage knob

moves the stage up or down

X-axis stage knob

moves the stage back and forth (left to right)

Fine focus knob

Regulates the focus. Can be used to get the best focus on low-power objectives and should be used for all focusing with high-power objective lenses. Adjusted never in a full circle.

Coarse focus knob

Moves the stage up and down to the right position for focusing the specimen. This knob should only be used with low-power objective lenses (4x and 10x). How we will focus initially.

Condenser lens

Changes the angle of the light

Iris diaphragm lever

Opening and closing the hole to control how much light comes through. Regulates the amount of light reaching the specimen.

Stage

Where your slide fits

Objective lense

4x ; 10x ; 40x

Revolving nose piece

How to make lenses move

Golden Rules

1) Must be in sharp focus at low power before we can proceed to high power

2) We can only use fine adjustment knob at high power

3) Never use the course adjustment knob at high power

How to obtain sharp focus on a specimen

1) Crank the stage all the way up using the coarse adjustment knob

2) Take the coarse adjustment knob and rotate it towards us about a quarter of a turn

3) We could take the revolving nosepiece and rotate the low-power lens into place (now we can use the fine adjustment knob to make subtle adjustments to bring into sharp focus)